Interop 2026 proposal window is now open
Seven months into the Interop 2025 project, the focus areas for this year are still being actively worked on. At the same time, the organizers are looking ahead: the submission form for Interop 2026 feature proposals is open from today through September 24, 2025. Anyone can submit ideas via the feature submission form, and all proposals will be evaluated according to the documented selection process.
What makes a viable proposal
The goal of Interop is to take features that have already completed the standards process and make them work consistently across browsers. A strong proposal should therefore be backed by a stable specification with no outstanding vendor objections. In past years, most accepted features had already shipped in at least one browser before being proposed.
A solid test suite is equally important. Since a feature's success in Interop is measured by how well browsers pass tests, proposals need to demonstrate that sufficient test coverage already exists. The Proposal Guide lists additional signals that can strengthen a submission.
Interop 2025 progress so far
For reference, the Interop 2025 focus areas started in February with the initial browser scores shown below.
Several features highlighted at the start of the project have since made notable progress. Same-document view transitions, for instance, are now available in Firefox Nightly as an experimental feature. The <details> element additions, including the ::details-content pseudo-element, shipped in Safari 18.4, which also landed the sideways writing mode values and brought that feature to Baseline Newly available.
The current Safari 26 beta includes support for overflow-block and overflow-inline, logical properties that were already in Chrome 135. These will become Baseline Newly available once Safari 26 reaches stable. The beta also contains CSS anchor positioning along with numerous other fixes that should improve Safari's Interop score.
In addition, mutation events have now been removed from all browsers. The Interop 2025 dashboard tracks these improvements, and several more browser releases are expected before the year ends.
Proposals for Interop 2026 can be submitted via the feature submission form until September 24.
